Hi,
Looking to improve our home insulation and wondered where best to start to get the best savings with quickest payback. Our house is a 5 bedroom detached house built in 2000/2001 in central Scotland (Kilmarnock). It is of brick and block construction with breeze-block inner and brick outer leaves. Windows are wooden framed double glazed. Heating is gas central heating with microbore distribution to room radiators.

My initial thoughts were to add a 200mm layer of loft insulation to the existing 70-100mm layer but I've just seen some figures which suggest I will only save £30 per year and given that it will cost £210 for 50 sq m of "space blankets" from B&Q to cover the unfloored section of my loft this is a 7 year payback which is not what I was hoping for.

My next thoughts are to improve draft proofing as there are a few gaps under skirting boards and around doors and windows that I could fill but this is more difficult to measure in terms of cost/benefit and will be time consuming.

I hope to change the windows for UPVC in a few years but can't afford it just now.

I'm not keen on cavity wall insulation as I believe the cavity is there for a reason and don't plan to bridge it. There is foil backed rockwool insulation between plasterboard and breeze block anyway so the walls shouldn't be too bad.

Anyway - any thoughts as to whether it is worth doing my loft or fixing draughts or anything else which might help keep the gas bills down? By the way my current gas consumption is around 26000 kwh per year which costs around £900 per year...

Cheers,
Craig.

[Edited on 28/12/2008 by craig1410]

I'm no expert, but i'd say go with cavity wall insulation. the cavity in the wall is there to give an air gap, this means (as i understand) if its cold outside, and warmer inside the house, the air gap in the wall has to cool down before the air inside the house is cooled. cavity wall insulation puts extra barriers and extra layers, so instead of 1 air gap, you get thousands of them, means it takes even longer to transfer the heat. just like your loft, and loft insulation.

you say the cavity is there for a reason, as i see it, cavity wall insulation was invented for a reason too.

it is rather cold outside today though, isn't it?


just read the edit bits, yeah, stopping draughts will make a huge difference though!

[Edited on 28/12/08 by blakep82]

In my house, 3 things made the biggest difference:

1. Fixing the draughts - the biggest thing being a second door in the hallway to act as an air-lock when going in and out.
2. Loft insulation. A lot of heat goes out that way.
3. Cavity wall insulation - I know you don't like the idea, but it made a huge difference to my house. Previously my house was always warm enough, until the cold winds blew. Then the house would chill down very fast. Now it doesn't chill anywhere near as fast.

The double glazing didn't make such a difference, apart from fixing all the draughts.

Talking about cavity wall insulation - in new houses they have to build in insulation by law these days, usually in the form of foam blocks in the cavity. Can't be all bad!

[Edited on 28/12/08 by David Jenkins]

Wood framed double glazing is pretty good if it has proper seals. I read specifications recently that suggested it was better than uPVC (I think due to the lack of internal metal surround). I definitely wouldn't want to change good newish windows.

Hi,
Thanks for your suggestions - much appreciated.

My objections to cavity wall insulation are more to do with concerns about dampness traversing the cavity from the outer leaf to the inner leaf. This is a heavily debated issue and there are many advocates of cavity insulation and many who frown upon it. I have read the arguments and counter arguments at length and my own conclusion is that I prefer to retain the cavity at least until my NHBC warranty is up to avoid any potential complications should a warranty claim be necessary (I hope it isn't mind...)

If, on the other hand I owned an older house then I would be more inclined to go for cavity insulation but I think it is still too early to determine whether using it in a modern house is going to cause dampness issues or not. To counter Blake's argument that cavity wall insulation is there for a reason, I would say it is there to make the manufacturers money and to help the government meet its targets for CO2 reduction - neither of these goals means that it is the best thing for my house...

On the subject of draughts, I have just noticed that my windows have a draught exclusion seal between the frame and the bit that opens and this is compressed to the point where it doesn't really seal any more. I wonder if I can replace this stuff with new or supplemental sealing strip? I think that would make quite a difference.

Cheers,
Craig.

quote:

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Originally posted by JonBowden
Wood framed double glazing is pretty good if it has proper seals. I read specifications recently that suggested it was better than uPVC (I think due to the lack of internal metal surround). I definitely wouldn't want to change good newish windows.

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over the last year i've had my cavity walls insulated and done the attic. The house is a lot warmer.

My dad has done the same - except being my dad he's seriously exceeded the reconmendations. His house now has the problem that its too warm at times. Brother has turned off the radiator in his room if he turns the pc on. i did the same when i turned the xbox on in my room.

Biggest thing stopping my house being as warm as my parents is drafts - which is what i'll work on over the next year.

Cavity wall insulation is cheap, especially if you get a grant, which we did a couple of years back. I think we only paid £75 for the job.

B&Q have started to sell thin loft insulation. It looks like plasticised foil coated bubble wrap. 6mm thickness of it has the insulating properties of 65mm of polystyrene (1.4 M K/W). A couple of layers of that under your loft boards would help.

Double glazing is expensive. You could replace your sealed units with K glass ones if you wanted to improve them. It would save on replacing the frames. If you want cheap, just make sure the frames are sealed to the walls properly.

ive just climbed down from my loft now!

B&Q had an offer on loft insulation, i got 100mm stuff, and 56 square meters was about £60 (it was half price). Im putting double layers in over the existing scrawny stuff. No need to get the bagged stuff, ive been tearing it all day and its not at all itchy!

Drafts is the number one thing to sort. Either expanding foam, decorators caulk or strips of whatever sort.

Its a shame that your house, being so new, wasnt built better. Its always harder to sort later. But you defiantely want something in the cavity insulating it. This will be a significant factor in your house if there is nothing in there. 100mm kingspan is nice if you're building a new wall, or thermal blocks, but for existing walls you just have to do what you can. You wont have a problem with damp IMHO.

When I extended into my loft I lined the rafters with 100mm Kingspan. The difference is amazing. The rads upstairs are turned off as the heat rising from downstairs keeps the loft really comfy and warm.

Would recommend it everywhere, under the floor, in the walls, above your head....

Current building regs recommend 10" of Rockwool in an 'open' loft. 4" of Kingspan is warmer

I got a load (36 rolls) of the Knauf space blankets from B&Q on Xmas Eve. They had them half price and 2 for 1 and if you spent more than £50 you got another 15% off. This offer finishes tomorrow though. This makes the 200mm space blanket only £2.55.

Steve

quote:

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Originally posted by craig1410
Blake's argument that cavity wall insulation is there for a reason, I would say it is there to make the manufacturers money and to help the government meet its targets for CO2 reduction - neither of these goals means that it is the best thing for my house...

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someone worked out that if you had one metre of insulation in your walls, and equivilent elsewhere, you wouldnt need central heating at all.

this is what my friends in the trade recommend:


1. stop cold air getting in - and hot air getting out. £1 shop draught excluders are the ultimate bang for buck

2. heat rises - loft insulation next, anything from 10 inches of rockwall, 100mm of kingspan, or 50mm of lambswool/fibre stuff.

3. cavity insulation - injecting polystyrene balls is cheap. just make sure you dont want a conservatory or extension in the near future, they will fall out (funny to watch)

4. good quality curtains. cheaper than double glazing.

5. heat source - insulate hot water pipes and tank. install a more efficient boiler.

Will

edit: if your house has a porch, USE IT!!! only open one door at a time to avoid loosing heat. avoid using backdoor if possible.

[Edited on 28/12/08 by dinosaurjuice]

First, and in answer to your question about best bang for your buck, the introduction of additional glass or mineral wool fibre roll or batts to the roof void will give a good improvement for a modest outlay.
Secondly, if you want to improve matters further, and assuming that you have a suspended timber floor and sufficent space between the underside of the floor joists and the solum, you could install insulation to the floor, staple netlon ( it looks like strawberry netting) to the underside of the floor joists and place more glass or mineral wool between each joist. At the date your house was built and assuming it got Building Warrant before the build date, it wouldn't have needed floor insulation, so an easy improvement is available here.

The cavity wall insulation insn't as bad as you think, the cavity is not to provide a pocket of insulated air, it's basically to stop driven rain going from the outer side of the wall to the inner. That's why wall ties have drips on them so any water that passes throuth the outer leaf and onto the tie drips of and down the cavity before it runs to the inner leaf blockwork. Cavity wall insulation installed by an approved installer using a product tested by BBA or similar will provide a big insulation improvement for a small outlay. The products used today are usually closed cell insulants to stop moisture migration across the filled cavity. I would say from both a personal and professional perpspective that done properly the introduction of cavity wall insulation is fine.
There are a few other things to consider, as others have said, introducing draught strips etc will help, you obviously in the future intend to change windows and doors, choose a low e glass with an inert gas filling for your windows, some glazing will give as low as a 1.1 U value. Finally, how efficent is your boiler, a boiler installed in a house from the early ninety's will be of poor efficency compared to current condensing combi boilers with TRV controls etc to all your rads. It's worth thinking about a change to your boiler, it's approaching 20 years old and is probably going to give you trouble soon anyway. If you want any more specific advice re what I've said drop me a U2U and I'll get in touch.
If you introduce more insualtion and make the house more air tight please ensure that you have good ventilation above the insulation in the roof space and below the floor as interstitial condensation could become a problem other wise.
Derek

quote:

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Originally posted by delboy
It's worth thinking about a change to your boiler, it's approaching 20 years old and is probably going to give you trouble soon anyway.

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I bet the best bang for your buck is foil-backing your radiators.

However for a more structural insulation I would succesively put on the whole package. Loft or roof insulation, cavity insultation, floor insulation, etc.

Now is the time to get started. Products are relatively cheap, and when the recession is over, energy prices will go sky-high.

Like Joel we have gone for the cheap deals on loft insulation at B and Q and put in 51 rolls the other weekend- depending on your energy costs it should be less than 7 years before it pays its way if you buy it economically, we are on the dreaded bulk LPG here so didn't hesitate.
As your house is relatively new it should be built to a half decent standard so savings may not be so dramatic,

BTW what sort of central heating controller do you have - is it 7 days and zoned?

quote:

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Originally posted by trextr7monkey
Like Joel we have gone for the cheap deals on loft insulation at B and Q and put in 51 rolls the other weekend- depending on your energy costs it should be less than 7 years before it pays its way if you buy it economically, we are on the dreaded bulk LPG here so didn't hesitate.
As your house is relatively new it should be built to a half decent standard so savings may not be so dramatic,

BTW what sort of central heating controller do you have - is it 7 days and zoned?

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Sorry, Craig, when I was answering your post I thought it had said built in 1990/91. To answer your question re floors, it could have insulation below the concrete floor slab. However, some builders, usually the big ones used an allowance in the Building Regs to trade off building elements. In other words they put no insulation in the floor and used heat loss calculations to show that even with no floor insulation that the house still met standards due to slightly less glass or slightly more wall insulation than a house designed to the minimum for each element would have acheived. The Building Regs in force in the late 90's and early 2000 were easy to manipulate in this manner. It's not so easy now. Basically what you're doing is going to help, but lots of small improvements will collectively make a difference. Eventually you will get to a point where you need to think about cavity wall insulation and new windows etc. Either that or go build a new house with insulation designed beyond those prescribed by the Buidling Regs. Just for info our current political masters want us to achieve zero carbon by 2050, so it looks like new houses in the future will have to have lots more insulation than at present.

No worries, forgive me if I'm not surprised that there are ways around the regs...

For info, the house was built by Barratt and is of the "Ascot" variety. The build quality is pretty bad, certainly from an internal fit and finish point of view. Also, the plumbing had to be redone twice due to lead contamination and the standard of plumbing is absolutely awful, as is the standard of joinery and plasterboarding. I'm a keen amateur and I could have easily put both the plumbers and the joiners to shame with my own skills!

The brickwork looks pretty good so I can work on the internals over the next few years and bring it up to standard.

Cheers,
Craig.